The first golfs balls were leather with a wet feather filling. As the ball dried the feathers expanded and the leather casing shrank giving the final ball a relatively smooth exterior and resilience. These "feathery" golf balls were used from the 14th and 15th centuries up until about the mid 19 century (see "Golf Balls", Golf For Women, May/June 1989, page 71). In 1848 a single piece golf ball called the "gutty" was introduced. This ball was made of gutta-percha, a packing material then used in imports from china. The "gutty" did not fly as well as the "feathery", however the "gutty" was less expensive, and lead to a wider acceptance of the game of golf among the middle and lower classes (see "The Curious History Of The Golf Ball" by John Martin, Horizon Press, New York 1968).
After introduction of the "gutty", it was noted that an older golf ball would often travel farther than a new golf ball. This was attributed to the nicks and scratches on the surface of the golf balls (see "Golfers Always Have A Ball" Professional Golfer, August 1967). Subsequently, different methods of adding markings at the surface of the balls were developed. This eventually lead to the development of the complex dimple patterns in use on golf balls today.
The primary purpose of dimples on a golf ball is to induce the balls boundary layer to transition from laminar to turbulent at an artificially low Reynolds Number, well within the range experienced by a golf ball under normal conditions. On a smooth ball, the transition occurs naturally at a Reynolds Number substantially outside of this range. For a golf ball, the advantage of a turbulent boundary layer is twofold: it dramatically decreases the aerodynamic drag experienced by the ball as it flies through the air; and, it increases and stabilizes the aerodynamic lift. This allows a dimpled ball to fly much farther than a smooth one. In fact, under identical driving conditions a dimpled ball will fly 100 to 150 yards farther than a smooth one.
The dimple patterns that can be used on golf balls vary greatly, with a majority of the patterns in use before the modern spherical or saucer (elliptical) shaped dimples being illustrated in "Antique Golf Ball Reference and Price Guide" by Leo M. Kelly, Old Chicago Golf Shop, Illinois 1993. Modern Dimple patterns and dimple profiles are perhaps best illustrated by those designs found in U.S. Pat. No. 4,936,587, assigned to Acushnet Company, which have garnered wide acceptance and use in the golf ball industry. Despite the use of a large variety of dimple patterns on golf balls there exists a continuing need for dimple patterns that allow for the production of golf balls that have better properties and/or which are easier to manufacture than prior art golf balls.
Golf balls can be used in variety of circumstances ranging from a professional golf tournament to a driving range. In each of these situations golf balls suffer from the wear and tear a ball is subjected to by being hit at great force with a golf club. In particular, iron type clubs having aggressive groove configurations can cause substantial abrasion damage to the ball's surface, which in extreme cases can negatively affect the flight performance. It also damages the cosmetic markings and symbols on the ball's surface, making them difficult to read. Accordingly, there is a continuing need for golf balls which have symbols that are readable for longer periods of time than golf balls of the prior art.
Prior patents have disclosed varying golf ball depression configurations, such as flat bottom dimples (U.S. Pat. No. 878,254); grooves with constant depth portions (U.S. Pat. No. 4,284,276) and circular dimples having depths related to a chord across the dimple (U.S. Pat. No. 4,979,747). However none of these prior art balls overcomes as many of the problems in the prior art as golf balls made according to the present invention.
Furthermore, none of these prior disclosures provides the dimple configuration of the present invention and the advantages it provides.
In spite of the dimples of the prior art which have circular or elliptical profiles, there is a continuing need in the art for golf balls having dimple configurations which impart improved performance properties.
Further, there is a need in the art for golf balls which provide improved contact between the club head and golf ball.
Also, there is a continuing need for golf balls which have been resistance to damage by abrasion with the club face.